APPARATUS FOR SECURING WORKING TOOL IN IMPACK-TYPE MACHINES

摘要

A percussive tool has a working tool mounted for reciprocations in a barrel. A collar is arranged between a shank and a working portion of the working tool. The shank of the working tool reciprocates in a guide bushing secured in the barrel to ensure reciprocations of the working tool. There is provide4d a member for determining the angular position of the working tool during the reciprications, the member comprising either the barrel proper in case of concrete breakers, or a hood, e.g. in chipping hammers. For positively controlling the angular position of the working tool, there is provided a spring having two portions of different cross-sectional configuration, a first portion being coupled for a combined rotation to the member determining the angular position of trhe working tool, and a second portion being of a cross-sectional configuration corresponding to the cross-sectional configuration of the working portion of the working tool.